Year	Percent
1991	15.461
1992	16.83
1993	16.959
1994	16.607
1995	16.487
1996	16.433
1997	16.529
1998	16.698
1999	16.621
2000	14.974
2001	15.153
2002	15.425
2003	15.538
2004	15.593
2005	15.739
2006	15.794
2007	15.729
2008	16.156
2009	16
2010	16.021
2011	16.074
2012	16.244
2013	16.612
2014	16.846
2015	16.474
2016	16.655
2017	16.866
2018	16.984
2019	17.102
2020	17.281
2021	17.419
2022	17.567